We give a new geometric model for the quantization
of the 4-dimensional conical (nilpotent) adjoint orbit
$O_\mathbb{R}$ of SL$(3,\mathbb{R})$. The space of quantization is the space of
holomorphic functions on $\mathbb{C}^2- \{ 0 \}$ which are square integrable
with respect to a signed measure defined by a Meijer $G$-function.
We construct the quantization out a non-flat Kaehler structure on
$\mathbb{C}^2 - \{ 0 \}$ (the universal cover of $O_\mathbb{R}$ ) with Kaehler potential
$\rho=|z|^4$.